Load isolation consumption management systems and methods

ABSTRACT

Disclosed herein are power management systems for controlling recorded electrical demand by isolating loads from a utility distribution grid connection. The loads are isolated when an energy storage system (ESS) is placed in series between the loads and the grid, with a charger that keeps the ESS from depleting and a power converter that provides energy to the loads from the ESS. A system controller may be enabled to manage the charging of the ESS by the charger relative to a consumption metric. In some embodiments, the loads are categorized, controlled, or curtailed by the controller and may be isolated from other loads. Some embodiments include bypass features or bimodal connections. Additional methods of control to prevent depletion of the ESS are also set forth. Systems herein can prevent or limit demand charges, protect the utility grid from backflow and other dangers, and raise the customer&#39;s effective utility service limit.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation application of U.S. patentapplication Ser. No. 13/460,538, filed 30 Apr. 2012 and entitled, “LoadIsolation Consumption Management Systems and Methods,” the disclosure ofwhich is incorporated, in its entirety, by this reference.

BACKGROUND

The present invention is directed to the fields of energy consumptionmanagement systems, electrical demand charge control, and relatedfields.

Electricity consumers in recent years have been faced with rising energycosts and rising needs to address environmental and efficiency concernsin the grid. Energy consumption management systems have been developedwith these needs in mind to reduce energy consumption during periodshaving higher electricity costs, to expand the availability of chargingelectrically-powered vehicles, to participate in demand responseprograms hosted by utilities, and to counteract the appearance of demandcharges assessed by utilities, among other goals. To prevent or diminishthe appearance of demand charges, typical consumption management systemsemploy curtailment techniques such as load shedding, prioritization, andcycling to reduce demand during peak periods when demand charges wouldotherwise be registered by utility meters. Some management systemsinclude energy storage devices such as battery banks that are dischargedat these peak times in such a manner that the net load on the grid ismitigated even if the usage of the loads at the site goes unchanged.

When using energy storage devices or generators to supply energy to asite for consumption management, a system controller monitors theoverall consumption of the site and discharges the energy storage orstarts up a generator when the consumption is too high. This gives riseto a number of problems. One is the delay between detecting excessconsumption and providing energy to the site for sites where an inverteris controlled in response to a command signal. The controller mustregister that the consumption has surpassed a limiting value, then thecontroller must send instructions to the energy storage or generator,and then the energy storage or generator must provide the energyrequired. It is common for a spike in demand to have already subsidedbefore the energy provision takes place, and even if the peak has notsubsided, the utility meter has already recorded at least a portion ofthe peak that exceeds the limiting value. These issues may not bepresent when an inverter is used that converts power on demand, but theload may still fluctuate dramatically enough that circuit breakers orprotective relays are tripped, and the load profile of a mitigated loadis usually still erratic.

The reactive design of these systems leaves uncertainty regarding howmuch consumption will actually be recorded by the utility. Highersampling rates tend to reduce the uncertainty and allow the system tomore closely follow an idea “flat-line” of consumption, but even at highsampling rates there is a chance that protection relays may be triggeredbefore action can be taken. Furthermore, sudden loss or gain of loadcreates a risk of back-feeding energy to the grid or tripping protectivebreakers that do not automatically reset. Back-feeding is dangerous tolocal utility providers as it adds to the risk of tripping networkprotectors. Additionally, the sampling rate and extreme twitchcapability of these systems drives up their complexity and cost, and candamage or at least excessively cause wear to energy storage devices,generators, switches, and other components.

BRIEF SUMMARY

Embodiments of the invention address issues present in the industry byproviding systems and methods for isolating loads from the utilitydistribution grid using an energy storage system (ESS). In someembodiments, a system topology is provided that places the ESS of aconsumption management system inline between a utility energy sourcesuch as a distribution grid connection and a load of the site. The ESSis charged by a charger such as a rectifier, and the ESS is dischargedthrough an inverter to the loads. In these embodiments, the load is“isolated” from the grid because its consumption, including its demandspikes or other fluctuations, is supplied by the reservoir of energystored by the ESS while the ESS is recharged at a relatively steady rateusing grid energy. Thus, to the utility meter, the load behind the ESSappears to be consuming energy at the rate that the ESS is chargedwhether or not its demand is erratically shifting. In some embodiments asystem controller is provided and enabled to control the charging of theESS relative to consumption metrics such as the present consumption ofthe load, the time that the ESS is recharged, the cost of electricity,the overall consumption of the site, etc. The ESS may act as a bufferbetween the grid and the load so that the system can react to demandfluctuations more slowly or gradually and helps to smooth out themetered load profile, providing greater predictability in demand chargesand triggering fewer protective relays or breakers.

In some embodiments, the consumption management system classifies loadsdifferently, and certain loads are controlled or curtailed by a systemcontroller in order to reduce energy consumption from the ESS. In someembodiments, bypass switches or automatic transfer relays are providedthat allow isolated loads to receive energy from the utility grid whilethe ESS is unable to provide energy in a manner that meets the needs ofthe loads. In some embodiments the ESS is bi-modally connected, allowingon-grid and off-grid operation of loads. In yet other embodimentsgenerators are provided that supplement energy provided from the utilitygrid. In additional embodiments a main breaker and panel board areprovided as part of the system.

Some embodiments of the invention provide methods employed by a systemcontroller in controlling the charging of the ESS to avoid depletion ordamage to other equipment.

Additional and alternative features, advantages, and embodiments of theinvention will be set forth in the description which follows, and inpart will be obvious from the description, or may be learned by thepractice of the invention. The features and advantages of the inventionmay be realized and obtained by means of the instruments andcombinations particularly pointed out in the appended claims. These andother features of the present invention will become more fully apparentfrom the following description and appended claims, or may be learned bythe practice of the invention as set forth hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

In addition to the novel features and advantages mentioned above, otherobjects and advantages of the present invention will be readily apparentfrom the following descriptions of the drawings and exemplaryembodiments.

FIG. 1 is a block diagram of an exemplary embodiment of the inventionhaving isolated loads at a utility customer site.

FIG. 2 is a block diagram of an exemplary embodiment of the inventionhaving categorized isolated loads at a utility customer site.

FIG. 3 is a block diagram of an exemplary embodiment of the inventionhaving limited categorized isolated loads at a utility customer site.

FIG. 4 is a block diagram of an exemplary embodiment of the inventionhaving bypass switch functionality at a utility customer site.

FIG. 5 is a block diagram of an exemplary embodiment of the inventionhaving alternative bypass switch functionality.

FIG. 6 is a block diagram of a bi-modally connected exemplary embodimentof the invention.

FIG. 7 is a block flowchart illustrating an exemplary control algorithmfor a system controller of the present invention.

FIG. 8 is a block flowchart illustrating an additional exemplary controlalgorithm for a system controller of the present invention.

FIG. 9 is a load profile graph showing the recorded demand behavior ofan exemplary consumption management system embodiment.

FIG. 10 is another load profile graph showing the recorded demandbehavior of an exemplary consumption management system embodiment.

FIG. 11 is a block flowchart illustrating an additional exemplarycontrol algorithm for a system controller of the present invention.

DETAILED DESCRIPTION

General Information

As used herein, an “electrical system” refers to an electrical circuit,device, or network of devices which consume or manipulates electricalenergy. Typical exemplary utility customer sites such as a place ofbusiness have multiple electrical systems connected to an electricalservice panel, and the electrical systems draw electrical energy from aconnection to an electrical utility distribution grid.

A “consumption management system” (or “CMS”) as used herein, refers to asystem of electrical devices and processes capable of affecting theconsumption of an electrical system, group of electrical systems, or ofa utility customer site as a whole. For example, a CMS may comprise asystem controller such as a computer that, when connected to anelectrical system, controls when loads of the electrical system areturned on or off. In some embodiments, a CMS may be used to executeinstructions for turning electrical systems on and off or to turnconsumption of an electrical system up or down (also referred to ascurtailment or load shedding), and other consumption control schemesknown in the art. Advantageous embodiments of a CMS affect consumptionthrough load mitigation, wherein an energy source such as an energystorage system (ESS) provides energy to a site or to electrical systems.An ESS is comprised of one or more energy storage devices, including,without limitation, a battery, capacitor, supercapacitor, flywheel, orother similar energy-storing device. Some consumption management systemsalso include a generation asset, such as a fuel-based generator andengine, photovoltaic generator, wind-based generator, fuel cell, orother similar electricity-generating device. Providing energy to a loador electrical system in order to reduce the consumption level of thatload or system may be referred to as mitigation or load shifting.

A CMS is beneficial to users because it can provide many different kindsof consumption management. The consumption management provided mayinclude (a) load leveling, wherein the consumption of a site orelectrical system is made more level over time (as opposed to risingduring peak consumption periods and dropping during low-consumptionperiods), or (b) peak mitigation, wherein spikes or plateaus of elevatedconsumption are mitigated or otherwise reduced in order to avoidincurring electrical utility-assessed demand charges or overloadingelectrical system capabilities.

Typical embodiments of the invention are directed to systems of a CMS,along with related methods, for managing electricity consumption in amanner that largely isolates fluctuations in electrical demand of anelectrical system or load from a utility meter. Preferred embodiments ofthe invention may provide the ability to:

(a) reduce demand charges,

(b) provide increased predictability and reliability in demand chargesby more effectively allowing load profiles to be “flat-lined,”

(c) protect utility provider and utility customer systems from theeffects of large swings in electricity consumption,

(d) raise the effective utility customer's consumption limit,

(e) increase permissible response time for CMS controls,

(f) provide emergency power during utility power outages,

(g) provide ability to sell power back to the utility provider,

(h) improve the power factor of the utility customer as seen by theutility provider, and

(i) more, as will be apparent to a person having skill in the art uponmaking or using embodiments described herein.

Load Isolation and Management

FIG. 1 shows a block diagram of an exemplary embodiment of the inventionwherein a utility customer site 100 is fitted with electrical devicesenabled to isolate fluctuations in load demand from the utilityprovider. The site 100 is provided power from the utility providerthrough a utility distribution grid connection 101 such as an AC mainline. The utility demand meter 102 registers consumption of all loads atthe site and is used to collect consumption data such as overall energyused (e.g., in kilowatt-hours) and maximum demand (e.g., in kilowatts)in a billing period. A typical customer location merely connects loads104 to the demand meter 102 through circuit breakers and panelboards,and immediate electrical demands from the loads are fulfilled by drawingenergy from the utility distribution grid connection 101.

According to embodiments of the invention, however, additional loads 106are connected to the utility distribution grid connection 101 through anenergy storage system (ESS) charger 108 that converts power from thegrid connection 101 to a form that charges an ESS 110 such as a bank ofbatteries, flywheels, capacitors, or other electrical energy-storingmeans known in the art. The ESS charger 108 may be embodied as arectifier to supply DC power to a battery-based ESS, an AC motor tocharge a flywheel-based ESS, or other comparable means to convert thepower provided from the utility grid connection 101 to a form of energystored in the ESS 110. The ESS 110 provides energy to a power converter112 which converts the energy into a form used to power the isolatedloads 106. The power converter 112 may include a DC-to-AC inverter,buck, boost, or buck-boost DC-DC converter, or other conversion deviceknown in the art that can transfer the energy from the ESS 110 in a formuseable by the loads 106. In a preferable embodiment, the powerconverter 112 is a 208 VLL DC-to-AC inverter that is capable ofproviding utility grid-grade AC power to the loads to which it isconnected. An output of the power converter may be controllable by asystem controller 114 or it may be able to provide output to the loads106 on demand and independent of a controller.

A system controller 114 monitors and manages the state of charge of theESS 110, the charging rate of the charger 108, and potentially otherfactors, such as the conversion rate of the power converter 112.Preferably, the system controller 114 is capable of determining the rateof charging performed by the charger 108, the state of charge of the ESS110, and the consumption of the loads through the power converter 112 inorder to ensure that the energy stored in the ESS 110 is stabilized. Thesystem controller 114 may also connect to an external network 116 forpurposes such as sending and/or receiving information and/orinstructions and directions with other devices or computers connected tothe network. Such a network may be, for example, a wide-area network(WAN) such as the Internet, or a local area network (LAN) linking thesystem controller to a localized network of devices.

The controller 114 may be enabled to manage the charging of the ESS bythe charger where the charging level is determined relative toconsumption metrics. Such consumption metrics may include, for example,(a) the present, historical, or projected consumption of the loads 106,(b) the times of day, week, month, or year at which the charger is used,(c) the cost of charging the ESS, (d) the cost to the utility provideror site operator of not charging the ESS, and/or (e) the overallconsumption level of the site.

The present consumption of the loads 106 can affect charging because thecharger 108 needs to provide energy to the ESS 110 at approximately theaverage rate of consumption of the loads over time when keeping the ESS110 at a stable state of charge. The controller 114 may also factor inthe historical consumption or a projected or predicted consumption ofthe loads 106 to determine whether the ESS 110 should be “pre-charged”to have more charge before a predicted or historical period of higheraverage load demand. Furthermore, the present consumption of electricityfrom the grid of the entire site may be an advantageous metric to use incontrolling the charging rate because loads other than the isolatedloads may cause the demand to rise to a threshold limit such as a demandcharge-inducing limit or a utility service limit. With the controllerenabled to manage charging according to the overall consumption,however, the charging level can be changed to limit driving theconsumption of the site from the grid as a whole to exceed these limits.

The time at which the charger is used may affect the charging leveloutput of the charger 108 because time may correlate with the price ofelectricity, and therefore the cost of charging the ESS, the expectedconsumption of the site in the future (suggesting a need forprecharging), whether a technician is on-site or available to monitorthe CMS, the temperature of the CMS (and therefore the efficiency),and/or other factors which may be taken into consideration whenimplementing and using the CMS.

The cost of charging the ESS can affect the charger 108 managementbecause in a CMS designed to reduce demand charges, the cost ofelectricity (i.e. price per kilowatt-hour), the cost of additionaldemand (i.e. price per kilowatt, such as a demand charge), and the costof wear on the CMS due to operating the charger (e.g., the cost of thereduced expected lifetime of batteries in the ESS). These can be drivingfactors in whether the charger 108 should be used and the rate at whichit should be used.

There may also be costs associated with not charging the ESS. Forexample, in some cases, the utility provider requests that consumptionis increased to artificially increase demand to compensate forover-supply conditions on the distribution grid. Here, the CMS operatormay use the charger to participate in this program by increasing thecharge rate of the ESS 110, even if the ESS 110 would not be charged atan elevated rate for another reason, because the operator would benefitfrom increasing demand for the utility provider.

The isolated loads 106 in this embodiment can be said to be “isolated”from the grid connection 101 because their energy demands are suppliedfrom the ESS 110 rather than directly from the grid connection 101through the demand meter 102, as is seen with the other loads 104. Thecharging of the ESS 110 is not controlled by the loads 106, though therate of ESS charging may be affected by the consumption of the loads106. The energy used over time (i.e. kilowatt-hours) by the isolatedloads 106 in such a system will generally match the energy used overtime of the same loads if they were not isolated, due to the ESS 110being recharged at roughly the average level of consumption of the loads106 over time, but instantaneous demand of the isolated loads 106 is notdetected by the demand meter 102. Furthermore, when the utilitydistribution grid connection 101 experiences a brownout or blackout, theisolated loads 106 are still able to temporarily receive energy that isstored in the ESS 110. The energy buffering resulting from the positionof the ESS 110 between the grid 101 and the loads 106 masks fluctuationsin demand of the loads 106 because they are absorbed by the ESS 110. Thedemand meter 102 may only see relatively small changes in the demand ofthe charger 108 that compensate for rises in the average consumption ofthe loads 106 served by the ESS 110.

The isolation of the loads 106 from the demand meter 102 has abroad-ranging impact on the design requirements and component makeup ofthe CMS as a whole. While some typical CMSs use bidirectional invertersto charge and discharge the ESS 110, the configuration of the embodimentof FIG. 1 requires only one direction of electrical energy flow from thegrid connection 101 to the loads 106, as indicated by the arrows of thefigure indicating a unidirectional flow of energy between the componentsof the CMS. This means that a bidirectional inverter can be replaced bymore specialized and typically less-expensive charger 108 and converter112 components. Nevertheless, in some embodiments an optionalbidirectional inverter or other converter may be used in place of theESS charger 108 to allow the ESS 110 to be both charged by the gridconnection 101 and to discharge energy back toward the demand meter 102or the grid connection 101. This may, allow the system to mitigateconsumption of the other loads 104 when appropriate or to respond to autility request for distributed generation on the grid. A bidirectionalsystem may also have the ability to discharge to the grid to sell powerback to the utility provider.

The CMS design of FIG. 1 allows more predictability and reliability indemand charges by allowing load profiles to be “flat-lined.” This isbecause the isolation of the loads 106 from the meter 102 keeps themeter from registering sharp changes in consumption over short periodsof time. Instead, the meter 102 detects the charging of the ESS 110through the charger 108, which is controlled to charge at a relativelysteady, “flat” rate, that typically only changes when the averageconsumption of the loads 106 changes for an extended period of time inorder to keep the ESS 110 from depleting over time. The rate ofconsumption of the charger then returns to the approximate averageconsumption of the loads 106 after the state of charge of the ESS isstabilized.

The configuration of components in the CMS also serves to protect theutility provider and utility customer systems from the effects of largeswings in consumption. In many CMSs, loads can create and eliminatespikes and valleys very quickly, and the system response lag behindthese changes can create undesirable results. For example, if the loadis low for some time, and the ESS 110 is recharging during that time,and then if the load suddenly spikes to a level near the utility servicelimit of the site, the ESS recharging might not stop quickly enough toprevent the consumption of the spike from being combined with theconsumption of the recharging action, and circuit breakers andprotective relays are tripped. The risk of such a scenario isdrastically reduced when isolating the loads from the meter because moretime is afforded to the system controller, charger, and ESS to react toswings in consumption rates.

In some embodiments, the CMS is capable of raising the effective utilitycustomer's consumption limit as well. The ESS 110 provides a temporaryenergy supply that can be used to serve loads that would otherwiseexceed the utility service limit of the site. The utility service limitas used herein refers to a rated maximum level of power drawn at onetime from the utility mains, which, if surpassed, triggers breakers orother protective devices put in place to keep demand within safe limits.If the consumption of the loads of the site having the CMS (e.g., theloads from loads 104 and charger 108) nears the utility service limit,isolated loads 106 may be operated even though they would force thetotal metered consumption to exceed the service limit if they wereconnected to the meter directly. In this situation, the charger 108keeps its consumption low enough to prevent the charger consumption frompushing the total consumption of the site over the utility servicelimit, even though the average consumption of the isolated loads 106 isgreat enough to deplete the ESS 110 over time. Therefore, the isolatedloads 106 can be at least temporarily powered by the ESS 110, and theoutput of the ESS 110 can exceed the charging rate of the ESS by thecharger 108 until the ESS is depleted.

Additional and Alternative CMS Configurations

In some embodiments, the layout of the CMS can be even more complex,wherein multiple power converters are used to connect the ESS 110 withdifferent kinds of isolated loads, such as different loads 118 requiringdiffering AC and/or DC voltages from a separate power converter 120.This allows the ESS 110 to be more efficiently used for multiple typesof loads (e.g., 106 and 118).

In some embodiments, certain isolated loads 122 may be even furtherisolated from the grid 101 by installing an additional charger 124, ESS126, and power converter 128 between the power converter (112 or 120)and the further-isolated load 122. This configuration compounds thelosses in efficiency caused by charging and converting the energy fromthe grid a second time, but it may be advantageous to further isolate orprovide separate converters to loads that have especially wide swings inconsumption so that the use of high-power converters and high-outputenergy storage can be tailored to be used for those loads in particular,since it may not be necessary to use the high-power equipment for therest of the loads being isolated from the grid. Therefore, thehigh-power components can have lower specifications and less associatedcosts.

FIG. 2 shows another embodiment of the invention bearing somealternative features. At this site 200, the loads are categorizedaccording to priority for monitoring and for control or curtailmentcapability. Some loads have continuous consumption 202, others areintermittent 204, and some are considered curtailable or controllableloads 206. These categories are representative of the multitude ofcategories that could be devised by one skilled in the art.

In this CMS, intermittent loads 204 may be monitored by the systemcontroller 208 in order to more effectively determine the charginglevels of the ESS charger 108. The charging level of the charger 108 mayneed to be increased when intermittent loads 204 are more active tocompensate for the increased drain on the ESS. If overall consumption ofthe site is determined by the system controller 208 (by reading thedemand meter 102, by measuring the loads 104 at the site, or by usinganother similar method) to be approaching a demand charge-inducing limitor a utility service limit for the site, the system controller 208 maytake action to curtail or control the consumption or power factor of thecurtailable or controllable loads 206 and prevent the consumption at thesite from reaching undesirable levels. In some embodiments, these loads206 are controllable by an interface link to the system controller 114.The interface link may be a wired or wireless connection through whichinformation can be transferred back and forth between the loads and thecontroller to carry out the control function of the controller.

Likewise, when the ESS 110 is low on energy and the charger 108 is notrestoring enough energy to the ESS 110 to keep it continuously providingenergy to the loads 202, 204, and 206, the curtailable or controllableloads 206 of this CMS may be directed to change (e.g. reduce or delay)their consumption requirements in order to prevent a loss of power tothe other loads 202 and 204. Such methods and other method embodimentsof the invention employed by the system controller 208 are described inmore detail below. In a preferable embodiment, thecurtailable/controllable loads 206 are EV chargers, which tend to beunpredictable as to when they will need to consume energy and the rateat which they will collectively draw energy, yet can be controlled byvarying their maximum output power or disabling the chargers altogether.

The direct access between the system controller 208 of this figure andthe demand meter 102 and loads 104 can be present in other embodimentsof the invention, where feasible, and the presence of those connectionsin this figure is not intended to imply a negative limitation on thoseother embodiments where such connections are not illustrated in thismanner.

FIG. 3 shows that in some embodiments it is preferable to isolate onlyintermittent loads and curtailable or controllable loads at the site.This embodiment allows the utility customer to reduce the size andstorage capacity of the ESS 110. Given the same size of ESS 110 andconsumption of the intermittent and curtailable/controllable loads, theembodiment of FIG. 3 has greater buffering ability than the embodimentof FIG. 2, since the drain on the ESS in FIG. 3 is lower during timeswhen the ESS is predominantly recharging as compared to the ESS of FIG.2, but the amount of energy in the ESS available for buffering willtypically be greater. This is at least partially because the continuousloads are not consistently draining the ESS during those periods.Furthermore, curtailable or controllable loads can be managed duringthose periods to allow the ESS to recharge even more quickly when neededwithout the consistent demand of continuous loads slowing down therecharging rate.

FIG. 4 shows another embodiment of a system of the invention wherein theutility customer site 400 has all of its loads 402, 404, and 406isolated from the grid connection 101. By isolating all loads from theutility grid 101, the utility customer is able to completely control theconsumption recorded by the demand meter by controlling the charger 108.In such an embodiment, the ESS 110 is preferably sized to be able tosupply energy to the loads equal to at least the maximum projectedenergy expended over the duration of a maximum projected peak inconsumption. The output power capacity of the ESS 110 and powerconverter 112 also should be greater than or equal to a peak consumptionlevel of the loads during the maximum projected peak in consumption toprevent needing to use an ESS bypass function when demand reaches highlevels. Other embodiments illustrated herein may include isolation ofall loads, even if not pictured in the figures as having thatfunctionality.

The system controller 408 of this embodiment is also enabled to controla transfer switch 410. A transfer switch 410 such as this allows theutility customer or controller to bypass the charger 108, ESS 110, andpower converter 112 completely, thereby taking some or all of the loads402, 404, and 406 out of isolation and supplying them with energy fromthe grid 101 without ESS buffering. In some embodiments, the systemcontroller 408 implements a control algorithm for the transfer switch410 or the transfer switch is designed with a fail-safe function whereinthe transfer switch is closed at critical times to prevent power loss tothe loads when the ESS is unable to provide energy to the loads asnecessary for their operation. For instance, to perform service of thecharger 108, ESS 110, or converter 112, the transfer switch 410 may beclosed to allow the loads to operate while the buffering components areinoperative. The charger, ESS, and/or power converter may have a modulardesign wherein the modular components are replaceable with othercompatible modules when load requirements, maintenance requirements, orjurisdictional code requirements for the customer change. In thesecases, having a bypass switch 500 allows the modules to be serviced orexchanged without interrupting supply to the loads. In theseembodiments, when the ESS 110 is depleted, the loads may still receivepower, but the charger 108 must increase its output to the ESS 110 toallow the ESS and converter 112 to be able to supply demand of the loadsif there are spikes in consumption while the ESS is low on charge. Thisscenario is preferably avoided so that the increased output of thecharger 108 does not incur new demand charges or cause the consumptionof the site to exceed a utility service limit. In the embodiment of FIG.4, the power converter 112 preferably is capable of synchronization withthe utility distribution grid lines when the transfer switch 410 isclosed, or the power converter 112 may be disconnected when the transferswitch 410 is closed to protect the converter and ESS if necessary, suchas to ensure safety in situations where the ESS is serviced while thetransfer switch is closed.

FIG. 5 shows an exemplary alternative bypass switch configurationembodiment. Here, a bypass switch 500 connects the output of the ESScharger 108 to the input of the power converter 112, bypassing the ESS110. This may be useful when the ESS is being serviced to ensure thatenergy is still provided to the loads. This embodiment may also beuseful in place of the embodiment of FIG. 4 when the charger 108 andinverter 112 can provide power conditioning to the loads in the absenceof the ESS 110 and the output of the charger and the input of theinverter are effectively the same. Furthermore, even if the ESS 110 isstill operative, the bypass switch 500 allows the customer to supplementthe power output of the ESS with energy from the grid through thecharger 108. Thus, the isolated loads receive energy through theinverter shown from the ESS 110 and the grid (via the bypass switch 500)simultaneously. This configuration is preferably implemented when thecharging rate of the ESS 110 is less than the consumption rate of theloads, the converter and inverter are capable of output that exceeds theinput and output of the ESS, and the ESS is not depleted.

FIG. 6 is an exemplary embodiment showing a bi-modal consumptionmanagement system wherein a line disconnect 600 provides a bimodalconnection between the utility distribution grid connection 101 the ESS110. As used in this embodiment, “bimodal” refers to a system that canprovide energy to loads whether it is off-grid or on-grid. Whileoperating off-grid, the CMS may supply energy to the loads using the ESS110, and the ESS would then be recharged when the connection between theESS and the grid is restored. In some embodiments a photovoltaic orother type of generator 602 may be employed in supplement to, or as analternative to, the ESS 110. Such a generator may include a fuel-basedengine and generator, a solar/photovoltaic generator, wind generator,fuel cell, or other such energy generation means known in the art. Agenerator of this kind allows the system to extend its effectiveoff-grid capacity by charging the ESS or decreasing the demand on theESS by supplying energy to the loads. A generator 602 may also beincluded in other embodiments, as will be apparent to one of skill inthe art.

A bimodal configuration of the system may be advantageous for sites thatoperate at levels of consumption that are near the utility servicelimit, as the system may be separated from the grid connection whenthere is a risk that demand will surpass the utility service limit orcause protective relays to be tripped. This configuration also providesan extra level of safety when service is done on the ESS 110, inverter112, or other components that can be disconnected from the grid usingthe line disconnect 600.

Charging Level Management Methods

FIG. 7 depicts a flowchart of an exemplary method of managing thecharging level of an energy storage system charger (e.g. charger 108).The process 700 begins as the system controller determines the presentdischarging power level of an ESS or an inverter of a CMS to a set ofloads in step 702. This entails measuring the rate of energy transferbetween the ESS and the loads and, in some embodiments, recording andstoring the information measured. The system controller next processesthis information to project an ESS depletion scenario (step 704). Adepletion scenario may include the time remaining until depletion of theESS at the current or recent average rate of ESS discharge, the expectedamount of discharge over that timeframe, and other related factors. Thescenario is used to produce a charging level for the charger that willprevent or delay the depletion of the ESS while a peak in load occurs sothat bypass switching measures will not be needed. The controller thenimplements the charging level determined in step 706 and checks to seeif the ESS is depleted in step 708. If the state of charge isacceptable, the controller resumes the process at step 702. If the ESSis depleted, the bypass features are used, wherein the bypass switch isclosed in step 710 and the ESS is recharged while the loads arereceiving power through the bypass switch route to the distribution grid(steps 712 and 714) until the ESS receives sufficient charge to open thebypass switch (step 716) and resume isolated load operation at step 702.

In some embodiments, the bypass switch provides an additional pathwayfor energy to reach the loads, such as is illustrated in FIG. 5. Inthese embodiments when the bypass switch is closed, the power providedby the ESS is supplemented by power provided from the distribution gridvia the charger. Thus, when executing the process 700, when the ESS isdepleted, the loads receive power through the bypass switch and the ESSsimultaneously, and the ESS may be set to recharge during that time aswell, as shown in step 712. When the state of charge has reached anominal level, the bypass switch may be opened to allow the loads toreceive energy exclusively from the ESS again.

In these embodiments, the definition of depletion of the ESS may varyfrom case to case. In some embodiments the ESS will be considereddepleted when it reaches zero state of charge, but in other embodiments,the ESS is “depleted” when the amount of charge falls below a thresholdlower limit. The threshold lower limit embodiments may be preferable inorder to prevent the ESS from falling below a critical amount of chargeand causing damage to the ESS or undue harm to the lifespan of the ESScomponents.

FIG. 8 depicts another exemplary method of managing the charging levelof the energy storage system charger. This process 800 begins by thesystem controller measuring and monitoring the site demand in step 802.If a peak is detected in step 804, charging power of the charger isreduced in step 806 and, in at least some embodiments, some or allisolated loads are curtailed to reduce the drain on the ESS charge.Next, the controller checks to see if the peak has ended in step 808. Ifit has ended, normal charging power is restored and curtailed isolatedloads are brought back to normal operations in step 810. If not, thecontroller checks to see if the ESS is depleted at step 812. If it isnot depleted, it resumes the process at step 808. If it is depleted, itfollows the bypass and recharge steps outlined in steps 710 through 716as described previously before reaching step 808 again.

In this embodiment, the controller responds to changes in overall demandof the site to reduce the charging power of the charger or thedischarging rate of the ESS, but the monitoring step 802 mayalternatively or additionally consider the other consumption metricsdiscussed previously, such as time, historical or projected consumptionof a load, cost of charging the ESS, etc. This method 800 isadvantageous when a peak in consumption would cause the charging of theESS to cause a new demand charge or cause the overall consumption of thesite to exceed a utility service limit. In step 806 of theseembodiments, the goal in reducing charging power is to cause thecharger's load on the grid to be low enough that it does not push theconsumption of the site to exceed a demand charge, utility service, orother limit at the site. By curtailing isolated loads in this step, theamount of time that the ESS can discharge is increased while thecharging power is reduced. If necessary, the bypass switch can be usedto supplement the power provided to the loads through the ESS with powerfrom the grid.

FIG. 9 shows an exemplary load profile that is possible to achieve usingsystems and methods described herein. Here, a total consumption profile900 is illustrated over a six-hour span of time. The total consumptionprofile 900 shows the amount of energy being consumed by isolated loadsat this site over that time period. A metered consumption profile 902 isalso shown over the same period of time which illustrates the loadprofile of the isolated loads as seen by the utility meter due to theload drawn by the charger for the CMS isolating the loads. The meteredconsumption profile 902 follows an approximate average consumption ofthe total consumption profile with brief higher demand periods thatappear when the total consumption profile 900 exceeds a peak threshold904.

The peak threshold 904 may be defined as a demand charge-inducing limit,wherein a new or increased demand charge will be incurred if consumptionexceeds the peak threshold for a sufficient length of time. The peakthreshold 904 may also be defined as a utility service limit, whereinprotective relays or circuit breakers would be tripped, or electricalservice equipment would fail, if the consumption exceeds the peakthreshold.

Here, it can be determined that when the consumption exceeds the peakthreshold for a given length of time, the charging rate of the chargeris increased to the peak threshold to prevent the ESS from depleting,and the charging rate is set to a level that is less than the peakthreshold 904 in order to keep a new demand charge from forming. Thebrief higher demand periods extend beyond the time when the peaks intotal consumption profile subside in order to recharge the ESS. Themetered load 902 of the site is significantly more flat-lined than thetotal consumption profile 900, providing many benefits as discussedpreviously. The maximum difference bracket 906 between the totalconsumption profile 900 and the metered consumption profile 902 in thisfigure illustrates the maximum magnitude of demand charge mitigationthat was achieved during this time period.

FIG. 10 shows a comparable load profile graph that may be producedaccording to another embodiment of the invention. As with FIG. 9, thetotal consumption profile 1000 shows the total consumption of theisolated loads over time, and the metered consumption profile 1002 isthe demand that is logged by the utility meter for that time as a resultof the charger drawing energy from the grid. Here, a utility servicelimit 1004 is the limiting threshold, so the metered consumption profile1002 reflects that when the utility service limit 1004 is surpassed bythe loads, the charger increases recharging up to the utility servicelimit 1004 without triggering an overload fault or circuit breaker.

The magnitude of the consumption of the isolated loads is permitted toexceed the utility service limit during these peaks because they areconsuming energy stored in the ESS. The maximum difference bracket 1006between the total consumption profile 1000 and the utility service limit1004 shows the amount of increased load capacity at the site as a resultof the loads being isolated from the grid by the ESS.

FIG. 11 is a flowchart showing another exemplary method of managing theconsumption of a site according to the present invention. The processshown 1100 determines the state of charge (SOC) of the energy storagesystem (ESS) at step 1102, and if the SOC is greater than or equal to atarget SOC, the charge rate for the charger of the ESS is set to zero instep 1104. If the SOC is less than the target SOC, the rate of change ofthe SOC is determined (e.g., as percent SOC per minute) and the currentcharge rate is measured from the charger in step 1106. If the chargerate is equal to the maximum charge rate of the charger and the SOC plusa timing factor times the rate of change of the SOC is less than orequal to an absolute minimum SOC, all curtailable loads are curtailed toa minimum consumption value, other loads are disabled, a transfer switchis closed, and the customer may be alerted of the conditions in step1108. If the charge rate is equal to the maximum charge rate of thecharger and the SOC is greater than the absolute minimum SOC, loads arecurtailed or disabled incrementally until the rate of charge increasesby a preset amount or maximum curtailment/disabling of loads is reachedin step 1110. However, if the current charge rate is less than themaximum charge rate and the rate of change of SOC is negative, a newcharge rate is set, such as the minimum value between the current chargerate minus the change in rate of SOC times a timing factor and themaximum charge rate in step 1112. Finally, if the current charge rate isthe maximum charge rate and the rate of change in SOC is positive, anypreviously curtailed or disabled loads are restored to powerincrementally or sequentially until the rate of change of SOC decreasesby a preset value but remains positive.

The exemplary process 1100 assists in keeping loads isolated behind theESS even though the loads have variable demand and the ESS has a varyingstate of charge because the charge rate and/or consumption rate of theloads being isolated by the ESS is manipulated to maximize the amount ofenergy in the ESS and the amount of time that the ESS can provide energyto the loads.

The steps of this method 1100 are intended to be representative and notexhaustive of the type of processes followed by a system controller ofthe present invention, and therefore the steps can be rearranged in somecases or may therefore be reliant on consumption metrics other than therate of change of SOC or the total SOC of the ESS, for example.

Miscellaneous Definitions and Embodiment Scope Information

Generally speaking, as used herein a “power converter” may refer to ageneric electric power converter, inverter, transformer, regulator,voltage stabilizer, rectifier, power supply unit, or other conversiondevice or combination of these devices that may be used to convert thevoltage, frequency, and/or phase of an electrical power source or signalfrom one form into another form.

As used herein, an “energy storage system” (“ESS”) is a means forstoring energy such as, for example, electrochemical batteries,compressed gas storage, pumped hydro storage, flywheel energy storage,capacitive energy storage, superconductive magnetic energy storage, fuelcell energy storage, combinations thereof, and other similar devices forenergy storage known in the art. If the energy storage device includes abattery, the battery types may include rechargeable or non-rechargeablechemistries and compositions, such as, for example, lead-acid, alkaline,secondary lead acid, lithium-ion, sodium (zebra), nickel-metal hydride,nickel cadmium, combinations thereof, and other energy storagechemistries known in the art. Energy storage devices may be comprised ofsmall or large numbers of cells, capacities, voltages, amperages, andother battery properties. They may be configured in unitary or modulardesigns and may follow standardized guidelines or customizedspecifications.

Some methods and systems of the embodiments of the invention disclosedherein may also be embodied as a computer-readable medium containinginstructions to complete those methods or implement those systems. Theterm “computer-readable medium” as used herein includes not only asingle physical medium or single type of medium, but also a combinationof one or more tangible physical media and/or types of media. Examplesof a computer-readable medium include, but are not limited to, one ormore memory chips, hard drives, optical discs (such as CDs or DVDs),magnetic discs, and magnetic tape drives. A computer-readable medium maybe considered part of a larger device or it may be itself removable fromthe device. For example, a commonly-used computer-readable medium is auniversal serial bus (USB) memory stick that interfaces with a USB portof a device. A computer-readable medium may store computer-readableinstructions (e.g. software) and/or computer-readable data (i.e.,information that may or may not be executable). In the present example,a computer-readable medium (such as memory) may be included to storeinstructions for the controller to operate the heating of the ESD andhistorical or forecasted temperature data for the ESD or itssurroundings.

The present invention may be embodied in other specific forms withoutdeparting from its spirit or essential characteristics. The describedembodiments are to be considered in all respects only as illustrativeand not restrictive. The scope of the invention is, therefore, indicatedby the appended claims rather than by the foregoing description. Allchanges which come within the meaning and range of equivalency of theclaims are to be embraced within their scope.

In addition, it should be understood that the figures described above,which highlight the functionality and advantages of the presentinvention, are presented for example purposes only and not forlimitation. The exemplary architecture of the present invention issufficiently flexible and configurable, such that it may be utilized inways other than that shown in the figures. It will be apparent to one ofskill in the art how alternative functional, logical or physicalpartitioning, and configurations can be implemented to implement thedesired features of the present invention. Also, a multitude ofdifferent constituent module or step names other than those depictedherein can be applied to the various partitions. Additionally, withregard to flow diagrams, operational descriptions and method claims, theorder in which the steps are presented herein shall not mandate thatvarious embodiments be implemented to perform the recited functionalityin the same order unless the context dictates otherwise.

Although the invention is described above in multiple various exemplaryembodiments and implementations, it should be understood that thevarious features, aspects and functionality described in one or more ofthe individual embodiments are not limited in their applicability to theparticular embodiment with which they are described, but instead can beapplied, alone or in various combinations, to one or more of the otherembodiments of the invention, whether or not such embodiments aredescribed and whether or not such features are presented as being a partof a described embodiment. Thus, the breadth and scope of the presentinvention should not be limited by any of the above-described exemplaryembodiments.

Terms and phrases used in this document, and variations thereof, unlessotherwise expressly stated, should be construed as open ended as opposedto limiting. As examples of the foregoing: the term “including” shouldbe read as meaning “including, without limitation” or the like; the term“example” is used to provide exemplary instances of the item indiscussion, not an exhaustive or limiting list thereof; the terms “a” or“an” should be read as meaning “at least one,” “one or more” or thelike; and adjectives such as “typical,” “conventional,” “traditional,”“normal,” “standard,” “known” and terms of similar meaning should not beconstrued as limiting the time described to a given time period or to anitem available as of a given time, but instead should be read toencompass conventional, traditional, normal, or standard technologiesthat may be available or known now or at any time in the future.Likewise, where this document refers to technologies that would beapparent or known to one of ordinary skill in the art, such technologiesencompass those apparent or known to the skilled artisan now or at anytime in the future.

A group of items linked with the conjunction “and” should not be read asrequiring that each and every one of those items be present in thegrouping, but rather should be read as “and/or” unless expressly statedotherwise. Similarly, a group of items linked with the conjunction “or”should not be read as requiring mutual exclusivity among that group, butrather should also be read as “and/or” unless expressly statedotherwise. Furthermore, although items, elements or component of theinvention may be described or claimed in the singular, the plural iscontemplated to be within the scope thereof unless limitation to thesingular is explicitly stated.

The presence of broadening words and phrases such as “one or more,” “atleast,” “but not limited to” or other like phrases in some instancesshall not be read to mean that the narrower case is intended or requiredin instances where such broadening phrases may be absent.

Additionally, the various embodiments set forth herein are described interms of exemplary block diagrams and other illustrations. As willbecome apparent to one of ordinary skill in the art after reading thisdocument, the illustrated embodiments and their various alternatives canbe implemented without confinement to the illustrated examples. Forexample, block diagrams and their accompanying description should not beconstrued as mandating a particular architecture or configuration.

Further, the purpose of the Abstract is to enable the U.S. Patent andTrademark Office and the public generally, and especially thescientists, engineers, and practitioners in the art who are not familiarwith patent or legal terms or phraseology to determine quickly from acursory inspection the nature and essence of the technical disclosure ofthe application. The Abstract is not intended to be limiting as to thescope of the present invention in any way.

What is claimed is:
 1. An electrical system for managing electricityconsumption of a load from an energy source at a site, the systemcomprising: a load at the site; an energy source connected to the site;an energy storage buffer configured to provide energy to the load, theenergy storage buffer electrically isolating electricity consumption ofthe load from the energy source, the energy storage buffer beingpositioned inline and in series between the energy source and the load;a switch, the switch being configured to electrically bypass the energystorage buffer when the switch is closed to allow electricityconsumption of the load from the energy source, the switch beingconfigured to isolate the load from the energy source when the switch isopen.
 2. The electrical system of claim 1, wherein the energy storagebuffer comprises an energy storage system (ESS), a charger, and a powerconverter, the charger, ESS, and power converter being positioned inlineand in series with each other.
 3. The electrical system of claim 1,wherein the energy source is a utility distribution grid.
 4. Theelectrical system of claim 1, further comprising a system controller,the system controller being configured to implement a control algorithm,the control algorithm comprising closing the switch when the energystorage buffer is unable to provide energy to the load.
 5. Theelectrical system of claim 4, wherein the energy storage buffer isunable to provide energy to the load due to depletion of charge of theenergy storage buffer.
 6. The electrical system of claim 4, wherein theenergy storage buffer is unable to provide energy to the load due to theenergy storage buffer being inoperative.
 7. The electrical system ofclaim 1, wherein the energy storage buffer comprises a power converter,the power converter being configured to be synchronized with the energysource upon closing the switch.
 8. An electrical system for managingelectricity consumption of a load from an energy source at a site, thesystem comprising: a load at the site; an energy source connected to thesite; a plurality of electrical buffering components configured toprovide energy to the load, the plurality of electrical bufferingcomponents electrically isolating the load from the energy source, theplurality of electrical buffering components being positioned inline andin series between the energy source and the load, the plurality ofelectrical buffering components having an energy source side and a loadside; a generator connected to the load on the load side of theplurality of electrical buffering components, the generator beingconfigured to provide energy to the load independent of the energysource.
 9. The electrical system of claim 8, wherein the generator isconfigured to provide energy to the load simultaneously with theplurality of electrical buffering components.
 10. The electrical systemof claim 8, wherein the generator is configured to provide energy to theload separately from the plurality of electrical buffering components.11. The electrical system of claim 8, wherein the plurality ofelectrical buffering components is bimodally connected to the energysource.
 12. The electrical system of claim 8, further comprising asystem controller, the system controller being configured to receive aconsumption metric, wherein the system controller is enabled to managethe charging of the plurality of electrical buffering componentsrelative to the consumption metric.
 13. The electrical system of claim12, wherein the system controller is enabled to increase or decreaseconsumption of the charger upon receiving a signal from the utilityprovider or a site operator.
 14. The electrical system of claim 8,wherein the generator is configured to provide energy to the load when ademand level of the load reaches a utility service limit.
 15. A methodof shielding demand fluctuations in an electrical load from an energysource, the method comprising: providing energy to at least one loadusing energy stored in an energy storage device, the at least one loadbeing isolated from an energy source by the energy storage device due tothe energy storage device being connected in series between the energysource and the at least one load; determining, via a system controller,that the energy storage device is inoperative or has a depleted charge;closing a switch, the switch bypassing the energy storage device,thereby providing energy from the energy source to the at least oneload.
 16. The method of claim 15, wherein the switch is configured tobypass a charger and a power converter.
 17. The method of claim 15,further comprising exchanging the energy storage device with anotherenergy storage device while the at least one load is provided energyfrom the energy source via the switch.
 18. The method of claim 15,wherein the energy source is a utility distribution grid.
 19. The methodof claim 15, wherein closing the switch prevents consumption of the atleast one load from exceeding a utility service limit.